Regenerative repeater



March 1954 R. M. M. OBERMAN ETAL 23,301

REGENERATIVE REPEATER 3 Sheets-Sheer 1 Original Filed Dec. 8, 1949 b1 JYAVAY 1N VEN TORS 'rzn' MARIE ROELOF mAhR OBERm/qq' AND AH-romE BY 5NITDERS March 16, 1954 R, M. M. OBERMAN ETAL Re. 23,801

REGENERATIVE REPEATER Original Filed Dec. 8, 1949 -5 Sheets-Sheet 2 INVENTORSI ROELDF P'IMRrErfmhRIE OBERMM AND AHTOIHE Reiuued Mar. 16, 1954 UNITED STATES PAT ENT OFFICE REGENERATIVE REPEATER,

Roelof M. M. Oberman, Voorburg, and Antonie Snijders, The Hague, Netherlands Original No. 2,599,345, dated June 3, 1952, Serial No. 131,742, December 8, 1949. Application for reissue September 16, 1953, Serial No. 380,639

(Cl. IT'S--70) 11 Claims.

Matter enclosed in heavy brackets I: appears reissue specification;

The distortion is caused by advanced and delayed transitions between mark and space elements, or by a loss of the rectangularity of these transitions. The advanced and delayed transitions mainly occur in radio transmissions owing to echo phenomena, while the loss of 1 rectangularity is caused in cables or the lil: The regenerative repeater according to the in vention, by means of short scanning impulses with constant intervals,- uses only a short middle portion of each received code element and this avoids the distorted transitions. The nature of the input code element defined by a scanning impulse, is transferred to a transmitting device having two stable positions. Dur- .ing the following interval the transmitting device maintains its position. Each subsequent scanning impulse ascertains whether the transmitting device should remain in the prevailing position, or whether it should be brought into the other stable position. [In the] The regenerative repeater according to the invention belongs to the kind in which the intervals between the scanning impulses are given by a local time basis, however, the location of the regenerated signals is determined by the input signals so that the regenerated signals are started by the transitions between the stop and start element of the subsequent input signals, which are subject to distortion.

With the regenerative repeaters of this kind hitherto known in the art, the rigid application of the principle mentioned hereinabove results in irregularities inthe sequence of the regenerated signals, corresponding to the accidental irregularities of the start-stop limits in the in put code, As all the other code elements of the regenerated code are determined by the constant impulse intervals, it is only the stop elements in which the irregularities are accumulated. Particularly if a delayed input element is followed by an advanced signal, the intermediate stop of the regenerated signal pair canbecome so. short'that a following receiving device falls out of synchronism, especially in case of a new unfavorable distortion.

in the original patent but forms no part of this matter printed in italics indicates the additions made by reissue.

It has been proposed to overcome this drawback by transmitting the first code in the transmission series with a longer stop element having a duration of 30 instead of 20 msec, however, it is clear that with a series of regenerative repeaters very short stop elements may occur owing to an accumulation of distortions, although about 7% of the transmission speed is sacrificed.

Moreover, it has been suggested to adjust the time basis of the scanning impulses so that it is faster than the time basis of the preceding transmitting device so that the stop elements in the regenerated code are lengthened at the expense of all the other code elements, which, as a matter of fact, are shortened. together with the intervals between the scanning impulses.

But for the loss of signalling speed this expedient in principle has the same drawbacks as the former one, though signals with stop elements that are longer than the start and combinations elements originate one station later. The local time'basis advance must be deter mined in accordance to the permissible transmission distortion; this has to be repeated cumulatively in case of a sequence of regenerative repeaters.

With the regenerative repeater according to the invention the mentioned drawbacks are overcome because the vibration generator contains a capacitor with a leakage resistor, arranged in such a manner that the charging condition of this capacitor admits the introduction of an impulse'train only after the regenerated signal has been transmitted with a stop element of a certain minimum duration.

By the application of this expedient the sec- 0nd of two closely succeeding signals is delayed so that the intermediate stop element is given a minimum duration at the expense of one or more succeeding stop elements. The admissibility of this solution of the problem is based on the discovery that a congestion of input signals can only occur in combination with enlarged interspaces in other parts of the telegram while the average speed is not changed and remains equal to that of the original sender.

According to an embodiment of the invention the time constant of the relevant capacitor with leakage resistor in the vibration generator is calculated in. such a manner that the lag between the last scanning impulse of an impulse train the first impulse of the next impulse train is equal to the interval timein the impulse train. This embodiment can be used if the, time basis of the regenerator is not slower than the time basis of the first sender. In order to allow an original sender to operate faster, the time basis of the regenerative repeater should. be adjusted so as to be faster, however, this advance is restricted to the slight adeviation which according to the recommendations of the C. C. I. T. (Comite Consulatif International Telegraphique) has a tolerance of i%%, While the transmission distortion is left entirely out of consideration. Moreover, in this case the time :basis advance {is :not cumulative for a series of subsequent regenerative repeaters. If in this embodiment the C. C. I. T. tolerance of 4% is to 'be maintained, the original sender device should meet .a higher demand of accurateness, so that this sender and the first regenerative repeater together satisfy the relevant tolerances If, e. the .original sender operates too fast, the regenerative repeater shouldbe allowed to operate A faster than the sender, in order to obtain 4% deviation from the standard in the regenerated code.

according to .a preferred embodiment o! the present invention the minimum delay between impulse trains chosen shorter than the interval time. A regenerative repeater according .to this embodiment can, even without time basis advance, handle signals originating from :a sender that is a little it'oofast. As a matter of fact, this embodiment involves the appearance of shortened stop elements in the-regenerated code, but these elements are iikewise restricted 'to "a :minimum duration, so that even in subsequent regenerative repeaters the shortening of the stop element is :not cumulative.

When "two widely interspaced signals are received by :a regenerative repeater "according to this embodiment, the second impulse train .is not produced immediately after the lapse of time determined by the capacitor and resistance mentioned hereinbefore, :but only :after the arrival of the start element of the second signal.

The invention furthermore relates to :a :regenerative repeater of the kind described, having an arrangement of capacitors :and resistances in the vibration generator which limits the stop elements of the regenerated code to a fixed minimum duration, the startestop device comprises a relay and :a diodeor rectifier cell :a-rraingedin'sudh a manner that this relay operates more slowly in one direction than in the other and therefore makes the regenerative repeater in the normal position insensitive to clicks of shorter duration than the operation time of the relay, which is predetermined according to the minimum stop element.

Thepredetermination of the min-imumduration of the regenerated stop elements also keeps the first scanning impulse of any impulse train apart from the beginning of the relevant start-element of the input signal, so that any start element containing an initial part of a certain duration does not contain ascanning impulse.

.If in the repeaters hitherto known in the vart via the receiving device the vibration generator is operated by a faulty short interruption of the transmission, the generator generates a complete impulse train.

In the :known regenerative repeaters this cannot be avoided in general, :because there always a chanceof correct scanning in the beginning of the start element. "The regenerative repeater according to Ethis LlDVEIItlOIlzdDBS not have this drawback; in case the vibration generator should be operated by clicks, it can be quickly restored to normal by means of the relay delayed "in zone 1direction before the first scanning impulse appears, provided the interference disappears in time.

The invention will be further explained with reference to the annexed drawings showing an =embodiment adapted to aifive-unit code with start and stop element, thus containing altogether seven elements per signal, each element of the ideal non-distorted code lasting 20 milli-seconds, andc'onsequently each signal 140 msec. It should however :be understood that the invention is not restricted to this five-unit code.

Figs. 1 and l are together a diagram of a regenerative repeater according to the invention; "and Fig. 2 is a plurality of graphs illustrating the operation of various parts of the regenerative repeater shown in Figs. :1 and 1 1 and .1 shoe .from left to right three pairs of pentodes 'B1a,'B1b; 32a, "Bat; and B321, 1331. In each pair the control grid of each tube is concrossw'ise with the anode of "the other tube :of the pair, but in each pair the coupling is of :a difierent .nature. In the right hand pair of tubes BSa and Bab the control grids are coupled over ohmic resistances with the opposite anodes. In

consequence thereof this pair of tubes has have alternative stable conditions, i. e. one in which :tuhe iBa-a and one in which :tub'e B31: is conducting, at least when both screen grids are imparted positive voltage over resistance Ron and R40, respectively. .If one of the -supply voltages of "the screen grid, for instance of the screen grid of tube Baa is interrupted, only one stable condition prevails with one tube i831 :non conducti'ng and other tube Bab conducting.

The input signal is received by the receiving relay "0, the armature o of which in the shown normal condition interrupts the screen :grid voltage for Bl'b, E22,, and. Biia. If the armature o is moved over by :a start element and these three screen grid voltages are applied, tube Bea remains non-conducting. Only when a negative impulse reaches the top of :a potentiometer formed by the resistance R34 and R35 f-rom'the tube BzafiBzb as more fully explained hereinafter, part of it via "capacitor C8 eaches the control grid of the tube B3b; as armature o has been moved :over from the position shown in the drawing, resistance R32 is short-cireuited and capacitor C7 does not receive a negative impulse. The impulse over capacitor C8 renders tuoe Bab nonconducting so that the voltage drop in the series resistance R38 is greatly reduced and the potential division over resistanccsRmRmR/w ismodified.

Now the control grid of 133a is imparted ta higher voltage over resistance R47 and tube B3!- becomes conducting. resistor R39 increases and in thedivision overresistances R39, R42, R45, the control grid voltage of tube 'Bsb drops via resistor R44. so that the new conducting condition is stabilized,

At a subsequent scanning impulse :at the top of "the potentiometer R34, R35 it depends on the position of armature 0, whether the present conducting situation of the tubes "Baa, Bab is maintained or exchanged. During the course or the scanning impulse train the screen grid supply is taken over :by the relay armature a, so that armature ovbecomes auai'lableilor the changeover function in the device formed by armature o with resistances R32, R34, and Rae. The anode currents of tubes Bar and Eat :fiow through the respective windings of the polar transmitting relsyz.

The pair of tubes Ba, Ba, together war "the The voltage drop across J auxiliary equipment more fully to be described hereinafter forms the vibration generator.

By the capacitive couplings C4 and C5 the conductivity of the tubes B212, 3% is alternated regularly as soon as both screen grids are fed with positive voltage over armatures or a, and resistors R15 and R21, respectively.

In th normal condition tube B21; is non-conducting, but the Voltage division over resistances R21, R22, R26, R27, R28, and R29 is so chosen that the operation of armature o by a start element and consequently the appearing of screen grid Voltage immediately renders the tube B25 conducting. The negative voltage pulse through capacitor C4 and resistance R25 in consequence of the downward jump of the anode voltage of tube B221, renders tube B211 non-conducting and this fact causes a positive impulse to be imparted over capacitor C5 and resistance R19 to the control grid of tube B221- The negative charge of the control grid of tube 132s leaks off over the high ohmic resistance R24, so that after some time tube B21: is rendered conducting again and the conductivity changes back.

The time constant of the system formed by capacitor C5 and resistor R20 plays a decisive part because the change is cont nued as long as tube Bzs has positive screen grid voltage, first over armature o, afterwards over armature a.

The two anode currents and the anode voltages have rectangular wave forms, and are in mutual counterphase. For a duration of 20 msec. per element the frequency is adjusted by resistance R21 to 50 0/5.; resistance R26 regulates the symmetry of the connection. When armatures o and a have both returned to normal, the circuit over resistance R11 causes a negative screen grid voltage so that tube B22 remains constantly nonconducting or becomes immediately non-conducting. By the jumps of the anode voltage of tubes B211, B211, positive and negative impulses are not only sent over capacitors C4 and C5 but also over capacitors C3 and C0.

The latter are in counterphase and succeed each other with intervals of msec. The positive impulses over capacitor C5 are diverted via the rectifier cell 8C1, so that only the negative impulses reach the transmitter as scanning impulses over the tap of the potentiometer R34, R35 of the changeover device. The first of these negative scanning impulses arrives 10 msec. after armature 0 has been moved by a start element; the subsequent scanning impulses have intervals of 20 msec. between one another.

The tubes Bla, B111 are in a semi-stable condition because the anode of tube B12 is coupled with the control grid of tube B11; over one winding of relay A and resistor R3 in parallel and resistances R7 and R13, while the coupling of the anode of tube Bib with the control grid of tube B15. is established over the other Winding of relay A. and resistor R12 in parallel and the capacitor 01. Thus tube B12 is normally conducting and tube Blb non-conducting, even when resistance R14 over armatures 0 or a supplies screen grid voltage to tube Blb. The changeover requires a negative voltage impulse originating from tube B2a over capacitor C3 and C1. After the negative charge on the control grid of tube B18. has leaked oil over resistance Rs, so that this control grid reapproaches the positive voltage of the voltage divider formed by resistances R41, R5, Rs, R16, the conductivity of tubes Bla, Bib is changed back to the stable side. The high ohmic resistance Re and the capacitor C1 are chosen so 6 that the tube 31a is rendered non-conducting and thus the tube Blb remains conducting for msec. Any readjustment is done by changing the position of the tap of resistance R5, but absolute synohronism with the vibration generator.

is obtained by the voltage impulses over capacitors C2, C1, which are superposed as ripple on the control grid voltage of tube B111.

Immediately after armature 0 has been moved over, the first of the impulses has the negative sign, with the consequence described above, while after 130 msec. a positive impulse brings the control grid of tube 313. beyond the threshold value thereby rendering tube B13 conducting and tube Bib non-conducting. The intermediate positive and negative impulses are without effect on the conductivity of tubes Bio. and E110.

The armature a of the polarized relay A follows thccondition of conductivity of tubes B11, Bib, the anode currents of which flow through the two main windings of relay A. At the start this happens with a delay of about 10 msec., because an extra winding of the start-stop relay A is short-circuiteol over the barrier cell S04. Thus a click moving over the relay armature o in less than,l0 msec. is not taken over by armature a and the screen grid voltage of tubes Blb and B2a becomes again negative, so that these two tubes become immediately non-conducting before a negative scanning impulse has been sent over capacitor C6 to the transmitter. After a successful start and the completion of the 130 msec. mentioned before, the armature a returns without delay to normal and stops the generator. The seventh scanning impulse intended for the stop element coincides with this moment. Moreover, at this moment a negative impulse through capacitor C5 and resistance R10 passes to the -con trol grid of tube B211.

During a certain time determined by the impedance values of capacitor C5 and resistance R20, a negative potential is maintained on the control grid of tube B211, so that this tube cannot become conducting, even if, shortly after the stopping of the generator, a new start element again imparts positive screen grid voltage over armature o and resistance R15. Resistance R23 could be omitted and the capacitor C5 and resistor R20 would maintain tube B2a non-conducting during exactly 10 msec. after the stop impulse; they also fix the half period of the rectangular voltages to 10 msec. It is, however, clear that this accumulation of functions is not a necessary limitation of the present invention.

If Within 10 msec. after the stop impulse a new start element arrives, tube B29, does not become conducting before the expiration of the entire 10 msec. and consequently the regenerated signal has a duration of msec. If the new input 1 start element appears later than 10 msec. after the stop impulse, the tube B211 is ready to fulfill its function; after having reached the threshold value of the control grid voltage, tube B23. remains non-conductive until the screen grid voltage is switched on, and with this delay the finished regenerated signal has been extended to more than 140 msec. in total. When the local time basis is perfectly synchronous with the transmitter such a waiting process can occur only once or a few times, until the regenerative repeater lags behind the primary transmitter by a time period corresponding to the greatest delay of a start element that occurred.

If the time basis of the regenerative repeater is a little faster than that of the primary transto which the time constant of this group in the spacing period is shortened 2 3:9. say '18 so that regenerated signals are issued of minimally :138 ti-X12 tor the start and combination elements, and :18 :msec. for the stop element.

EH :the local time basis is perfectly synchronous Wj-thitihe transmitter, delays-Tare encountered with almost all the signals. The average and most rfrequently occurring duration of the regenerated signals is 3549-3111886 with loneer andishortcr signals distributed accordance with the theory probability. With this embodiment the local time {can be somewhat slower 1311 343118 time basis of the primary transmitter without .clroo :ping synchroniam; thus ii the first six eiements rare vsomewhat lengthened, this may be cornpcm w sated by the seventh =(stop) element. The mini- ;duration :of this stop element is only osters :mined by the admitted speed difference, while the transmission distortion only appears in the distribution of longer and shorter stop elements :over :a greaterperiod of time.

As the latter embodiment allows a relative ,ireeolom of time basis adjustment, it is possible .0 make use of locally available time vclevices such as the power supply ifrequencyrf-or :theadjustment or even for the (operation :of the impulse se orator.

Fig. 1' shows a \quadripole ,key S1 Zfor adjusting of the vibration generator by means of a so c./s.

standard ,freguenoy. The generator is brought i to uninterrupted vibration and -the{standard :fr-eiquency is conducted to an extra winding of the .zrecciv-ing relay L1] 0. The neon dischargin lamp NB [switched in by the .key 5,] shows a beat between both frequencies.

Furthermore Fig. 1- shows the rectifier cells in $02 and 3C3, which prevent certain undesirable couplings. The resistances ,Rs, R12, ,Rai'and R49 vby pass the windings of relays A-iandz, r spec =tively, and thus protect the screen grids when the relays A or Z are exchanged which would otherwise act as anodes. The resistances Bio, and E343 apply the correct cathode voltages and the ripple filter consisting of resistor L1 and capacitor Q11 protects the voltage sources V1, V2. 1

Fig. 2 shows various currents, yoltages, relay positions in the regenerative repeater zacacoroing to .Figs. 1- :and 11 oirepresentszthe received input signal -.c ontrolling the position of the armature o of the receivin relay :9 ."shown in Fig. 13. "The first "start relates to the first signal of a message, so :thatit is assumed 'for'this example that thisfirst start is preceded by astop pcriociduringwhich the transmitter'sends acon- -stant normal current over "the .line.

The .two control :griil voltages "Vga vgbg and the two .anorle currents lee and Iabf or :the vibratiomgenerator 1 2a, B2 are indicated behind the symbol .The line I :shows the positive and negative impulses which are .sentover the capacitor C:

"to the start device B144, (Bit.

cooperation of the "rectifier 58:01 pass from the mibmtion generator 33a, Bob P11911116 change-over device ;for the transmission device.

control grid voltages You and 37. 1:, and the two anode currents Ian :and Tab of the startstop device .EBla, 58in are shown behind :the syrin- 1101 T531.

The position of *the annatune a .of relay ,A is shown heh ind ithe :symbol a; it follows .on 'the avkole:anodeourrentslw and lab of the :start stop device. but in doingso itthasforthe eltmimh ition of clicks an operational xielay :in one direcwhen the armature .a is :movecl over spacingitozmarking, .as a .resultm :thashortcircuiting :of one winding 'of relay :A by the mom iBchind rthe symbo'l 583 the two anode currents of the Echange-over device 1133a, Bah :are shown to which the operation of transmission relay 1 corresponds with some delay as shown behind the symbol Z. 'The last three .zg-raphs show ithe shape of the revgveherated signal. The graph so! H s for the pairlof ttubes B2 shows the operation iof the vibration generator. The latter is started by the input signal -:.and then accomplishes its operation without being influenced by his signal. ilihezmomeni; when the generator is ready tooreact :to asubsequent start is indicated by the line. This moment is fixed 'by the time constant of the group vcapacitor C5 and resistors R2o, .wi'iich after the moment 1 30? that is the moment at which the control grid voltage V g for the seventh time becomes negative, brings about the shortened generator step.

if the start of the next input signal comes 'later than the moment indicated :by the line for instance at 'the'time indicated by the line Q in '2, the next impulse train is normally generated by the start of the input signal.

If, however, the start of thenext "input signal arrives earlier than the moment indicated 5b."? the line for instance at the time intimated by line P in. Fig. 2,' the new impulse train is not generated directly by the new input start but :first the -moment vindicatuecl by the line X3. is awaited. In this case the impulses follow the course indicated in the figure by dash lines.

llhe application of the invention is not stricted to a construction of the regenerative repeater or its parts as described in the before mentioned embodiment, but the receiving clevice, the change-over device, the tremsmissitrrl device, the vibration generator and the start stop canbe realized, electronically and/or electromechanically various manners.

"We claim:

LIn a regenerative repeater for telegraph signals including successive trains of impulses in a start-stop code, in combination, 311831151?- solving the impulses; a vibration generator connected to receiving soas to-bestarted iby the same on reeeption of the first train of impulses forming part of a telegraph signal; a "transmission device retransmitting the signals "received "by said receiving means, said transmissiondevice having two stable confiitions assumed by the same one at a time, under joint control ;o'f said receiving means and said vibration gencrater; 1a start-stop device electrically connected to the output of said vibration generator so as "to becontrollecl by the same, said start-stop device including two tubes, one of saidtubes being normally in conductive condition and the other of said tubes being normally in non-conductive condition, said tubes being gmutually connected in a semi-stable relation; and switching "means 9 connected in the output of said start-stopdevice and controlling the operation of said vibration generator.

2. In a regenerative repeater for telegraph signals including successive trains of impulses in a start-stop code, in combination, means receiving the impulses; a vibration generator connected to said receiving means so as to be started by the same on reception of the first train of impulses forming part of a telegraph signal, said vibration generator including two tubes acting in counterphase, one of said tubes of said vibration generator being normally non-conductive; a transmitting device retransmitting the signals received by said receiving means, said transmitting device being adapted to assume any one at a time of two alternative stable conditions controlled by said receiving means and aiTected by said vibration generator; a start-stop device electrically connected to the output of said vibration generator so as to be controlled by the same, said start-stop device including two tubes in semi-stable relation, one of said tubes of said start-stop device being normally conductive and the other tube of said start-stop device being normally non-conductive, said two tubes of said start-stop device having each a control grid, said control grid of said normally conductive tube of said start-stop device being capacitively coupled to the anode of said normally nonconductive tube of said vibration generator; and switching means connected to the output of said start-stop device and controlling the operation of said vibration generator.

3. In a regenerative repeater for telegraph s'gnals including successive elements, in a startstop code, in combination, means receiving the elements of the signals; a vibration generator connected to said receiving means so as to be started by the same on reception of the first ele ment forming part of a telegraph signal, said vibration generator including two tubes, one of said tubes of said vibration generator being normally non-conductive and the other being normally conductive, the conductivity of said tubes of said vibration generator alternating so as to generate rectangular pulses being in counterphase to each other; a transmitting device retransmitting the signals received by said receiving means, said transmitting device being adapted to assume any one at a time of two alternative stable conditions under the control of said receiving means and under the control of the transients produced by said vibration generator; a start-stop device electrically connected to the output of said vibration generator so as to be controlled by the same, said start-stop device including two tubes in semi-stable relation, one of said tubes of said start-stop device being normally conductive and the other tube of said startstop device being normally non-conductive, said two tubes of said start-stop device having each a control grid, said control grid of said normally conductive tube of said start-stop device being capacitively coupled to the anode of said normally non-conductive tube of said vibration generator, whereby said vibration generator produces voltage pulses inverting the conductivity of said tubes of said start-stop device; and switching means connected to the output of said start-stop device and controlling the operation of said vibration generator independently of the condition of said receiving means.

4. In a regenerative repeater for telegraph signals including successive elements, in a startstop code, in combination, means receiving the elements of the signals; a vibration generator connected to said receiving means so as to be started by the same on reception of the first element forming part of a telegraph signal, said vibration generator including two tubes; a plurality of capacitors and leakage resistors connected, respectively, in series between said tubes of said vibration generator rendering one of said tubes of said vibration generator normally nonconductive and the other normally conductive; a transmitting device retransmitting the signals received by said receiving means, said transmitting device being adapted to assume any one at a time of two alternative stable conditions predetermined by said receiving means, said transmitting device being affected by said vibration generator; a start-stop device electrically connected to the output of said vibration generator so as to be controlled by the same, said startstop device including two tubes in semi-stable relation, one of said tubes of said start-stop device being normally conductive and the other tube of said start-stop device being normally nonconductive, said two tubes of said start-stop device having each a control grid, said control grid of said normally conductive tube of said startstop device being capacitively coupled to the anode of said normally non-conductive tube of said vibration generator; a leakage resistance connected to said control grid of said normally conductive tube of said start-stop device whereby the conductivity of said tubes of said start-stop device is inverted by the first pulse produced by the starting of said vibration generator and is restored to normal after the negative potential of said control grids have been discharged gradually by said leakage resistances connected to said control grids, when one of the pulses produced by said vibration generator completes the discharging of said control grids at a sharply defined moment; and switching means connected to the output of said start-stop device and controlling the operation ofsaid vibration generator.

5. In a regenerative repeater for telegraph signals including successive elements, in a startstop code, in combination, means receiving the elements of the signals; a vibration generator connected to said receiving means so as to be started by the same on reception of the first element forming part of a telegraph signal, said vibration generator including two tubes; a plurality of capacitors and leakage resistors connected, respectively, in series between said tubes of said vibration generator and rendering one of said tubes of said vibration generator normally non-conductive and the other normally conductive so that said vibration generator produces rectangularly-shaped voltages; a transmitting device retransmitting the signals received by said receiving means, said transmitting device including two tubes each being adapted to asssume any one at a time of two alternative stable conditions determined by the condition of said receiving means and affected under the control of said vibration generator, one of said tubes of said transmitting device being normally conductive and the other non-conductive in one of the two alternative stable conditions; a potentiometer having taps capacitively coupled with the control grids of said tubes of said transmitting device, respectively; a capacitive coupling between the anode of said normally conductive tube of said vibration generator and said potentiometer;

11 a start-stop device including two tubes, one of said tubes of said start-stop device being normally conductive and the other non-conductive; a capacitive coupling between the control grid of said normally conductive tube of said startstop device and the anode of said normally nonccnductive tube of said start-stop device and the anode of said normally non-conductive tube of said vibration generator; a leakage resistance connected to said control grid of said normally i device over said leakage resistances connected thereto; and switching means connected to the 7 output of said start-stop device and controlling the operation of said vibration generator.

6-. In a regenerative repeater for telegraph signals including successive elements, in a startstop code, in combination, means receiving the elements of the signals; a vibration generator connected to said receiving means so as to be started by the same on reception of the first ele ment forming part of a telegraph signal, said vibration generator including two tubes; a plurality of capacitors and leakage resistors connected, respectively, in series between the anode of one of said tubes of said vibration generator and the control grid of the other of said tubes of said vibration generator and vice versa so as to afiect said vibration generator by said receiving means after the lapse of a predetermined time period according to the charging condition of said: capacitors; a transmitting device retransmitting the signals received by said receiving means, said transmitting device including two tubes each being adapted to assume any one at a time of two alternative stable conditions determined by the condition of said receiving means and affected under the control of said vibration generator, one of said tubes of said transmitting device being normally conductive and the other non-conductive in one of the two alternative stable conditions; a potentiometer having taps capacitively coupled with the control grids of said tubes of said transmitting device, respectively; a capacitive. coupling between the anode of said normally conductive tube of said vibration generator and said. potentiometer; a rectifier arranged for admitting only negative transients of the impulses to said transmitting device; a start-stop device including two tubes in semistable relation with each other, one of said tubes of said start-stop device being normally conductive and the other non-conductive; a capacitive coupling between the control grid of said normally conductive tube of said start stop device and the anode of said normally non-conductive tube of said start-stop device and the anode of said normally non-conductive tube of said vibration generator; aleakage resistance connected to said control grid. of said normally 7 conductive tube of said start-stop device, whereby the conductivity of said tubes of said startstop device after having been inverted by the first voltage pulse of said vibration generator is restored to normal in response to said vibration generator producing the last of a predetermined number of impulses which suddenly completes the gradual discharge of the negative potentials of the control grids of said tubes of said startstop device over said leakage resistances connected thereto; and switching means connected to the output of said start-stop. device and controlling the operation of said vibration generator.

7. In a regenerative repeater for telegraph signals including successive trains of impulses in a start-stop code, in combination, means receiving the impulses; a vibration generator connected to saidreceiving means so as to be started by the same on reception of the first train of impulses forming part of a telegraph signal, said vibration generator including two tubes acting in counterphase, one of said tubes of said vibration generator being normally non-conductive; a transmitting device retransmitting the signals received by said receiving means and regenerating the same under control of said vibration generator; a start-stop device electrically connected to the output of said vibration generator so as to be controlled by the same, said start-stop device including two tubes in semi-stable relation, one of said tubes of said start-stop device being normally conductive and the other tube of said start-stop device being normally non-conductive, said two tubes of said start-stop device having each a control grid, said control grid of said normally conductive tube of said start-stop device being capacitively coupled to the anode of said normally non-conductive tube of said vibration generator; switching means connected to the output of said start-stop device and controlling the operation of said vibration generator independently of the condition of said receiving means; and additional means for delaying the operation of said switching means in one direction thereof.

8. In a regenerative repeater for telegraph signals including successive trains of impulses in a start-stop code, in combination, means receiving the impulses; a vibration generator connected to said receiving means so as to be started by the same on reception of the first train of impulses forming part ofa telegraph signal, said vibration generator including two tubes acting in counterphase, one of said tubes of said: vibration generator being normally non-conductive; a transmitting device retransmitting the signals received by said receiving means and regenerating the same under control of said vibration generator; a start-stop device electrically connected to the output of. said vibration generator soas to be controlled by the same, saidstart-stop device including; two tubes in semi-stable relation, one of said tubes of said start-stop device being normally conductive and the other tube of said start-stop device being normally non-conducting, said two tubes of said start-stop device having each a control grid-said control grid of each normally 60H, ductive tube of said start-stopdevice being capactively coupled to the anode of said: normally nonconductive tube of said vibration generator; a switching relay connected to the output, of said start-stop device and: controlling the operation of said vibration generator independently of the condition ofsa-id receiving means; and means including a rectifier for delaying the operation of said switching relay in one switching direction thereof.

9. In a regenerative repeater for telegraph signals including successive series of impulses in a start-stop code, in combination, a receiving relay having an armature; a vibration generator ineluding: two tubes, one of said tubesof said vibration generator being normally conductive and the other of said tubes of said vibration generator being normally non-conductive, said vibration generator being connected to said armature of said receiving relay so that said armature of said receiving relay modifies the screen grid voltage of said normally non-conductive tube of said generator directly upon reception of the first of a series of impulses forming part of the telegraph signal; a transmitting device adapted to assume any one at a time of two alternative stable conditions predetermined by the position of said armature of said receiving relay and controlled by said vibration generator; a start-stop device including two tubes in semi-stable relation to each other, one of said tubes of said start-stop device being normally conductive, the other of said tubes of said start-stop device being normally non-conductive, a capactive coupling between the control grid of the normally conductive tube of said start-stop device and the anode of said normally non-conductive tube of said vibration generator; a polarized switching relay connected to the output of said start-stop device and having an armature controlling the operation of said vibration generator by applying a screen grid voltage to said normally non-conductive tube of said vibration generator independently of the position of said armature of said receiving relay; and means adapted to said polarized switching relay for delaying the operation thereof in one switching direction whereby the regenerative repeater in the normal condition thereof is rendered insensitive to clicks having a shorter duration than that determined by said means.

10. In a regenerative repeater for telegraph signals including successive series of impulses in a start-stop code, in combination, a receiving relay having an armature; a vibration generator including two tubes, one of said tubes of said vibration generator being normally conductive and the other of said tubes of said vibration generator being normally non-conductive, said vibration generator being connected to said armature of said receiving relay so that said armature of said receiving relay modifies the screen grid voltage of said normally non-conductive tube of said generator directly upon reception of the first of a series of impulses forming part of the telegraph signal; a transmitting device adapted to assume any one at a time of two alternative stable conditions predetermined by the position of said armature of said receiving relay and controlled by said vibration generator; a start-stop device including two tubes in semi-stable relation to each other, one of said tubes of said start-stop device being normally conductive, the other of said tubes of said start-stop device being normally non-conductive; a capacitive coupling between the control grid of the normally conductive tube of said start-stop device and the anode of said normally non-conductive tube of said vibration generator; a polarized switching relay having two windings and connected to the output of said start-stop device and having an armature controlling the operation of said vibration generator by applying screen grid voltage to said normally non-conductive tube of said vibration generator independently of the position of said armature of said receiving relay; and means including a rectifier connected in series with one of said windings of said switching relay, said means being adapted to said polarized switching relay for delaying the operation thereof in one switching direction whereby the regenerative repeater in the normal condition thereof is rendered insensitive to clicks having a shorter duration than that determined by said means.

11. In a regenerative repeater for telegraph signals including successive series of impulses in a start-stop code, in combination, a receiving relay having an armature; a vibration generator connected to said receiving means so as to be started by the same on reception of the first element forming part of a telegraph signal, said vibration generator including two tubes; a plurality of capacitors and leakage resistors connected, respectively, in series between the anode of one of said tubes of said vibration generator and the control grid of the other of said tubes of said vibration generator and vice versa so as to afiect said vibration generator by said receiving means after the lapse of a certain time period; a transmitting device retransmitting the signals received by said receiving means and adapted to assume one of two stable conditions under the control of said receiving means and of said vibration generator; a start-stop device electrically connected to the output of said vibration generator and controlled thereby, said start-stop device including two tubes, one of said tubes of said start-stop device being normally conductive and the other non-conductive, said tubes of said startstop device being connected with each other so as to be in semi-stable relation; a switching relay connected to the output of said start-stop device and controlling the operation of said vibration generator independently of the condition of said receiving means; means adapted to said switching relay for delaying the operation thereof in one switching direction; and a rest contact connected to one of said capacitors of said vibration generator, whereby said armature of said receiving relay modifies the charging position of said capacitor connected thereto, thereby changing the time period during which said vibration generator cannot be started by said receiving means.

ROELOF M. M. OBERMAN. ANTONIE SNIJDERS.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS Number Name Date 2,406,096 Morrison Aug. 20, 1946 2,430,547 Anderson et a1. Nov. 11, 1947 2,454,089 Rea Nov. 16, 1948 2,474,490 Pelle June 28, 1949 

